U.S. patent application number 10/796528 was filed with the patent office on 2004-09-23 for holder-mounted optical element.
This patent application is currently assigned to Alps Electric Co., Ltd.. Invention is credited to Kikuchi, Kimihiro.
Application Number | 20040184164 10/796528 |
Document ID | / |
Family ID | 32984725 |
Filed Date | 2004-09-23 |
United States Patent
Application |
20040184164 |
Kind Code |
A1 |
Kikuchi, Kimihiro |
September 23, 2004 |
Holder-mounted optical element
Abstract
Provided is a high-precision holder-mounted optical element that
makes it possible to correct a volume error of an optical element
material. In a holder-mounted optical element 1 where an optical
element 20 is accommodated into a cylindrical holder 10, the holder
10 has a thin deformation portion 12 that is deformed by the
pressure applied from the inner circumferential side thereof and a
surplus portion 21a, which press-contacts with the deformation
portion 12, is formed in the optical element 20.
Inventors: |
Kikuchi, Kimihiro;
(Miyagi-ken, JP) |
Correspondence
Address: |
Brinks Hofer Gilson & Lione
P.O. Box 10395
Chicago
IL
60610
US
|
Assignee: |
Alps Electric Co., Ltd.
|
Family ID: |
32984725 |
Appl. No.: |
10/796528 |
Filed: |
March 9, 2004 |
Current U.S.
Class: |
359/819 |
Current CPC
Class: |
G02B 7/02 20130101 |
Class at
Publication: |
359/819 |
International
Class: |
G02B 007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 18, 2003 |
JP |
2003-073215 |
Claims
What is claimed is:
1. A holder-mounted optical element in which an optical element is
accommodated into a cylindrical holder, wherein the holder has a
thin deformation portion that is deformed by pressure applied from
an inner circumferential side thereof, and a surplus portion, which
press-contacts with the deformation portion, is formed in the
optical element.
2. A holder-mounted optical element according to claim 1, wherein
the surplus portion of the optical element is composed of a surplus
of an optical element material, and the deformation portion is
deformed by pressure applied from the surplus portion.
3. A holder-mounted optical element according to claim 2, wherein
the thin deformation portion is formed in a part of the side
surface of the holder, and the surplus portion is formed to
outwardly protrude from a circumferential portion of the optical
element.
4. A holder-mounted optical element according to claim 2, wherein a
thin collar portion is formed on the inner circumferential side of
the holder, the collar portion serving as the deformation, and the
surplus portion is formed around a tip portion of the inside of the
collar portion.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a holder-mounted optical
element in which a holder and an optical element are formed as a
single piece, and more particularly, to a holder-mounted optical
element formed by press-forming an optical element material within
the holder.
[0003] 2. Description of the Related Art
[0004] Optical elements, such as a lens mounted in the pickup head
of a CD player and a lens used in a digital camera, require high
precision when they are mounted. For example, as disclosed in
patent document 1, in order to satisfy this requirement, a
holder-mounted optical element in which a holder holds an optical
element is generally manufactured, and its mounting position is
adjusted by the holder, thereby improving mounting accuracy. The
holder-mounted optical element is formed in such a manner that an
optical element material, which is arranged inside a cylindrical
holders is softened by heating, the softened optical element
material is press-formed by a metal mold to form an optical
element, and at the same time, the optical element is compressed to
the holder. In this way, the optical element and the holder are
formed as a single piece.
[0005] [Patent Document 1]
[0006] Japanese Unexamined Patent Application Publication No.
3-265529 (FIG. 1)
[0007] However, in a case where an optical element material is
press-formed, if there is any error in the volumetric metering of
the optical element material, the thickness of the optical element
material is changed. As a result, optical performance deteriorates,
and an ideal optical location should be obtained for adjustment and
fixation, causing problems in terms of performance and location
determination.
[0008] To solve such problems, the volumetric metering of the
optical element material should be precisely preformed to reduce
the volume error. However, in order to make sure to obtain the
desired effects, it is necessary to handle not only the volume of
the optical element material but also the holder shape with high
precision. However, in this case, material and processing costs
increase.
SUMMARY OF THE INVENTION
[0009] The present invention is designed to solve such problems,
and it is an object of the present invention to provide a
high-precision holder mounted optical element that makes it
possible to correct for errors in the volumetric metering of the
optical element material.
[0010] To achieve this object, a holder-mounted optical element is
provided, in which an optical element is accommodated into a
cylindrical holder, wherein the holder has a thin deformation
portion that is deformed by pressure applied from an inner
circumferential side thereof, and a surplus portion, which
press-contacts with the deformation portion, is formed in the
optical element.
[0011] Also, according to the present invention, the surplus
portion of the optical element is composed of a surplus of an
optical element material, and the deformation portion is deformed
by the pressure applied from the surplus portion.
[0012] Furthermore, according to the present invention, the thin
deformation portion is formed in a part of the side surface of the
holder, and the surplus portion is formed to outwardly protrude
from a circumferential portion of the optical element.
[0013] Moreover, according to the present invention, the holder has
a thin collar portion on the inner circumferential side, the collar
portion serving as the deformation portion, and the surplus portion
is formed around a tip portion of the inside of the collar
portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a cross-sectional view of a holder-mounted optical
element according to a first embodiment of the present
invention;
[0015] FIG. 2 is a cross-sectional view of a lens holder and a lens
material according to the first embodiment of the present invention
before press forming is performed;
[0016] FIG. 3 is a cross-sectional view illustrating a
manufacturing state of the holder-mounted optical element according
to the first embodiment of the present invention;
[0017] FIG. 4 is a cross-sectional view of a holder-mounted optical
element according to a second embodiment of the present
invention;
[0018] FIG. 5 is a cross-sectional view of a lens holder and a lens
material according to the second embodiment of the present
invention before press forming is performed; and
[0019] FIG. 6 is a cross-sectional view of a manufacturing state of
the holder-mounted optical element according to the second
embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] Preferred embodiments of the present invention will now be
described with reference to the drawings. First, a first embodiment
of the present invention will be described. FIG. 1 is a
cross-sectional view of a holder-mounted optical element according
to the first embodiment of the present invention. FIG. 2 is a
cross-sectional view of a lens holder and a lens material according
to the first embodiment of the present invention before press
forming is performed. FIG. 3 is a cross-sectional view illustrating
a manufacturing state of the holder-mounted optical element
according to the first embodiment of the present invention.
[0021] A holder-mounted optical element 1 according to the present
invention is used for, for example, pickup heads of CD players or
digital cameras and includes a cylindrical lens holder 10 and a
spherical lens 20 accommodated into the lens holder 10, as shown in
FIG. 1.
[0022] The lens holder 10 for holding the lens 20 and determining
the location thereof in an optical device is made of aluminum or
stainless steel through a cutting process or casting process. The
lens holder 10 includes attaching portions 11, which serve as
reference surfaces when they are attached to an optical device, and
a thin deformation portion 12 continuously formed with the
attaching portions 11 on the inner circumferential side thereof. An
outer circumferential gap portion 13 surrounded by the attaching
portions 11 and the deformation portions 12 is provided on the
outer circumferential side of the deformation portion 12. Here, the
deformation portion 12 is deformed such that its central portion is
outwardly curved in the diameter direction, that is, towards the
outer circumferential gap portion 13.
[0023] A glass lens 20 is accommodated into the lens holder 10.
Both surfaces of the glass lens 20 are spherically convex and are
formed by press-forming a lens material 20a shown in FIG. 2. Also,
the glass lens 20 is pressed to the lens holder 10 by the pressure
applied at the time of press forming and is thus integrated with
the lens holder 10. A circumferential portion 21 of the glass lens
20 has a surplus portion 21a that protrudes from the entire surface
of the glass lens 20 to the outside.
[0024] The lens material 20a is composed of an optical glass
material. For example, the optical glass material may be a lead
oxide-based glass material SFS01. Here, the lens material 20a
intentionally has a surplus in addition to a volume required for
forming the glass lens 20. In this manner, a volume error of the
conventional lens material 20a is included in the surplus. Thus, at
least the proper volume of the lens material 20a required for
forming the glass lens 20 can be secured.
[0025] Here, in an initial state of the lens holder 10 that is
formed by a cutting process, etc., the deformation portion 12 is
formed nearly vertically with respect to the attaching portions 11.
However, by the pressure applied when the glass lens 20 is
press-formed, the surplus of the lens material 20a presses the
deformation portion 12, and then the deformation portion 12 is
outwardly curved in the diameter direction thereof. Then, the
surplus of the lens material 20a entirely goes into a space formed
inside the deformation portion 12 due to the deformation of the
deformation portion 12. In other words, the surplus of the lens
material 20a, which corresponds to the volume of a material that is
unnecessary to the formation of the glass lens 20, and the volume
error are absorbed by the deformation of the deformation portion
12. As a result, it is possible to form a high-precision lens 20
having the desired shape.
[0026] However, if the deformation portion 12 has high rigidity,
the deformation portion 12 is easily not deformed by the pressure
applied from the surplus of the lens material 20a, and thus the
surplus becomes an error in forming the lens 20. On the contrary,
if the deformation portion 12 has low rigidity, it is easily
deformed by the pressure applied from the surplus of the lens
material 10a and is then excessively deformed more than the amount
of deformation required for absorbing the surplus. In addition, if
the rigidity is low, the shape of the lens holder 10 cannot be
maintained. In other words, the deformation portion 12 preferably
has rigidity that allows it to properly deform, not to excessively
deform, due to the pressure applied from the surplus of the lens
material 20. By selecting a thickness and a material that satisfy
the above conditions for the rigidity of the deformation portion
12, the deformation portion 12 can function more effectively.
[0027] Next, a method of manufacturing the holder-mounted optical
element 1 will be described. FIG. 3 shows a manufacturing apparatus
for manufacturing the holder-mounted optical element 1. A
manufacturing apparatus 60 includes an upper die A comprising an
upper inner die 61 and an upper outer die 62, and a lower die B
comprising a lower inner die 63 and a lower outer die 64. The lower
inner die 63 and the lower outer die 64 are provided on the lower
side of the upper inner die 61 and the upper outer die 62. Also, an
outer diameter die C is provided to surround the upper die A and
the lower die B.
[0028] The upper inner die 61 and the lower inner die 63 are formed
in a substantially cylindrical shape. Transfer surfaces 61a and 63a
for forming a spherical lens are formed at the lower end of the
upper inner die 61 and the upper end of the lower inner die 63,
respectively.
[0029] In the meantime, the upper outer die 62 and the lower outer
die 64 are situated on the outer circumferential sides of the upper
inner die 61 and the lower inner die 63, respectively, and are
formed in a cylindrical shape. The thickness of the upper outer die
62 and the lower outer die 64 are approximately equal to that of
the lens holder 10 described above, and the inner diameter of the
outer diameter die C is approximately equal to the outer diameter
of the lens holder 10. Furthermore, the upper inner die 61 and the
upper outer die 62 may slide independently.
[0030] When the holder-mounted optical element 1 is manufactured,
first, the lens holder 10, which has been previously subjected to a
cutting process to have predetermined dimensions, is mounted on the
lower outer die 64, and the lens material 20a is mounted inside the
lens holder 10 (FIG. 3A).
[0031] Here, although not shown in FIG. 3, a heating member, which
is provided on the outer circumferential side of the lens holder
10, heats the lens holder 10. In addition, the lens material 20a is
heated above its softening temperature. Furthermore, the lens
material 20a in a preheated state may be mounted inside the lens
holder 10.
[0032] Once the lens material 20a is softened by heating, press
forming is performed on the lens material 20a (FIG. 3B). More
specifically, the upper outer die 62 is first moved downwardly with
respect to the lens holder 10 mounted on the lower outer die 64,
and the lens holder 10 is compressed and fixed between the upper
outer die 62 and the lower outer die 64. At the same time, the
upper inner die 61 is moved downwardly with respect to the softened
lens material 20a mounted on the lower inner die 63, and the lens
material 20a is pressed by the transfer surface 61a of the upper
inner die 61 and the transfer surface 63a of the lower inner die
63. Thus, the lens 20 of which both surfaces are spherically convex
is formed. The press forming is performed under the conditions
where the viscosity of the lens material 20a is above a glass
transition point and below a glass softening point.
[0033] Further, once the lens material 20a is pressed, the surplus
of the lens material 20a expands due to the applied pressure and
presses the deformation portion 12 of the lens holder 10 to
outwardly deform in the diameter direction thereof. Then, the
surplus of the lens material 20a goes into the inside of the
deformation portion 12, thereby forming the aforementioned surplus
portion 21a.
[0034] The above is the first embodiment according to the present
invention. Hereinafter, a second embodiment of the present
invention will be described. FIG. 4 is a cross-sectional view of a
holder-mounted optical element according to the second embodiment
of the present invention. FIG. 5 is a cross-sectional view of a
lens holder and a lens material according to the second embodiment
of the present invention before press forming is performed. FIG. 6
is a cross-sectional view of a manufacturing state of the
holder-mounted optical element according to the second embodiment
of the present invention.
[0035] A holder-mounted optical element 2 according to the second
embodiment is used for, for example, pickup heads of CD players or
digital cameras, as in the first embodiment. As shown in FIG. 4,
the holder-mounted optical element 2 comprised a cylindrical lens
holder 30 and a spherical lens 40 that is accommodated into the
lens holder 30.
[0036] The lens holder 30 is made of aluminum or stainless steel
through a cutting process or casting process. On the inner
circumferential side of the lens holder 30, a thin collar portion
32 is formed at a location that is approximately similar to one
surface of the lens 40, with a filling groove 31 sandwiched
therebetween. A tip portion of the collar portion 32 is curved in
the outside direction.
[0037] A glass lens 40 is accommodated into the lens holder 30. The
lens 40, of which both surfaces are spherically convex, is formed
by press-forming the lens material 40a as shown in FIG. 5. In
addition, the glass lens 40 is compressed to the lens holder 30 by
pressure in press forming and is then integrated with the lens
holder 30. A filling convex portion 41, which is filled into the
above-mentioned filling groove 31, is provided with a part of the
outer circumferential portion of the lens 40. Moreover, a surplus
portion 41a is formed around the tip portion of the collar portion
32 of the filling groove 31.
[0038] The lens material 40a intentionally has a surplus in
addition to the volume required for forming the lens 40, as in the
first embodiment of the present invention. Also, in this
embodiment, the volume required for forming the lens 40 includes
the volume of the filling convex portion 41.
[0039] Here, in an initial state of the lens holder 30 that is
formed through a cutting process, the collar portion 32 is formed
in a flat shape as shown in FIG. 5. However, the lens material 40a
goes into the filling groove 31 due to the pressure applied when
the lens 40 is press-formed, and the surplus of the lens material
40a inside the filling groove 31 presses the collar portion 32 from
the inside thereof to the outside. Thus, the tip portion of the
collar portion 32 is outwardly bent, and the filling groove 31
expands. The surplus of the lens material 40a entirely goes into
the expanded portion of the filling groove 31. Thus, the surplus of
the lens material 40a, which is the volume not required for forming
the lens 40, and a volume error are absorbed by the deformation of
the collar portion 32. As a result, it is possible to form a
high-precision lens 40 having the desired shape. Furthermore, the
requirement for rigidity of the collar portion 32 is the same as in
the first embodiment of the present invention.
[0040] Hereinafter, a method of manufacturing the holder-mounted
optical element 2 will be described. A manufacturing apparatus 60
for manufacturing the holder-mounted optical element 2 shown in
FIG. 6 is identical to that of the first embodiment and will not be
described. In the manufacturing method of the holder-mounted
optical element 2, first, the lens holder 30, which has been
previously subjected to a cutting process or casting process to
have predetermined dimensions, is mounted on the lower outer die
64, and the lens material 40a is accommodated into the lens holder
30 (FIG. 6A). At this time, the lens holder 30 is mounted such that
a surface provided with the collar portion 32 faces the lower outer
die 64. Then, the lens holder 30 and the lens material 40a are
heated. When the lens material 40a is softened by heating, press
forming is performed on the lens material 40a (FIG. 6B).
[0041] Furthermore, when the lens material 40a is pressed, the lens
material 40a goes into the filling groove 31 due to the applied
pressure. Then, the surplus of the lens material 40a expands and
presses the collar portion 32 from the inside of the filling groove
31 towards the outside to deform the collar portion 32. The surplus
of the lens material 40a goes into the expanded portion of the
filling groove 31 formed by the deformation, thereby forming the
surplus portion 41a.
[0042] The above is the description of the first and second
embodiment according to the present invention. In the above
descriptions, a method of manufacturing a spherical convex lens is
explained. However, the present invention is not limited thereto,
but may be applied to lenses in other shapes, such as a concave
lens, etc. Also, the present invention is not limited to the
lenses, but may be applied to other optical elements, such as a
diffraction lattice integrated with a holder, etc.
[0043] According to the present invention, a holder includes a thin
deformation portion deformed by the pressure applied from the inner
circumference thereof, and an optical element is provided with a
surplus portion that press-contacts with the deformation portion.
In this way, a volume error of an optical element material during
the formation of the optical element is absorbed by the deformation
of the deformation portion. Therefore, it is possible to precisely
form an optical element and to form a holder-mounted optical
element having a high-precision optical element, without improving
the precision of the holder.
* * * * *